Case of the shakes (6)
I believe the answer is:
quiver
I believe this clue is a double definition.
'case' is the first definition.
(quiver is a kind of case)
'the shakes' is the second definition.
(thesaurus)
'of' is the link.
(Other definitions for quiver that I've seen before include "Tremble - case for arrows" , "Receptacle in which archer keeps arrows" , "Tremble and shake, or receptacle for arrows" , "Arrow-holder; shake" , "Arrow case" .)